/*
 * Copyright (C) 2007 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.collect;

import com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.Iterator;

/**
 * An iterator which forwards all its method calls to another iterator. Subclasses should override
 * one or more methods to modify the behavior of the backing iterator as desired per the
 * <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p>
 * <b>{@code default} method warning:</b> This class forwards calls to <i>only some</i> {@code
 * default} methods. Specifically, it forwards calls only for methods that existed
 * <a href="https://docs.oracle.com/javase/7/docs/api/java/util/Iterator.html">before
 * {@code default} methods were introduced</a>. For newer methods, like {@code forEachRemaining}, it
 * inherits their default implementations. When those implementations invoke methods, they invoke
 * methods on the {@code ForwardingIterator}.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */
@GwtCompatible
public abstract class ForwardingIterator<T> extends ForwardingObject implements Iterator<T> {

    /** Constructor for use by subclasses. */
    protected ForwardingIterator() {}

    @Override
    protected abstract Iterator<T> delegate();

    @Override
    public boolean hasNext() {
        return delegate().hasNext();
    }

    @CanIgnoreReturnValue
    @Override
    public T next() {
        return delegate().next();
    }

    @Override
    public void remove() {
        delegate().remove();
    }
}
